1. Field of Invention
This invention relates to the field of solar energy and specifically for using concentrated sunlight for the concurrent generation of electricity within the same system as heating of a fluid for heating applications.
2. Related Art
Typical solar energy systems generate electrical power by either the direct conversion of concentrated or unconcentrated sunlight using solar cells (concentrated photovoltaic, CPV), or by using concentrated solar thermal (CST) energy to generate a pressurized vapor for turning a turbine-generator.
Concentrated photovoltaic (CPV) systems have a moderate efficiency of about 40% under a concentration of 500 suns and at an ambient temperature of 25 degrees C. The solar cells are sensitive to temperature, however, so that the efficiency drops to about 35% at about 100 degrees C., which highly concentrated sunlight is capable of achieving as shown in the use of concentrated sunlight to boil water for evaporation systems. In addition, concentrated photovoltaic (CPV) systems need a two-axis solar tracking and are expensive. As such, the return of investment period for localized installations is many years.
Concentrated solar thermal (CST) energy systems, on the other hand, can and must operate at a high temperature, and may reach a thermal efficiency of 60-80%. Collector to grid energy conversion losses, however, lowers the overall efficiency to about 15%. In addition, turbine-generator systems have inherent safety issues and are high maintenance, which raises the cost of the delivered power. As such, concentrated solar thermal (CST) energy systems are not suitable for localized installations.